The present invention relates to producing special effects to complement displayed video information and, in particular, to the use of Publish/Subscribe technology to distribute special effects to users.
A “Publish/Subscribe” system is a type of messaging application in which the providers of information (publishers) are decoupled from the consumers of that information (subscribers) by means of a broker. Typically, in such a system, a number of publishers publish messages to a broker on particular topics (e.g. news, weather, sport). Subscribers register their interest in such topics via subscription requests received at the broker. For example, a subscriber may request to receive any information published on the weather, while another subscriber may desire information on the news and sports. Publishers are not concerned with where their publications are going, and subscribers are not interested in where the messages they receive come from. Instead, the broker manages the distribution of the messages to make sure that they arrive at the correct destination according to valid subscriptions registered in the broker. A broker may also ensure that messages are distributed in the correct format and may also validate the authority of each publisher to publish to the subscribers which have subscribed to the particular topic on which the message is published.
In general terms, a publisher generates a message that it wants to publish and defines the topic of the message. The broker receives the message from the publisher and distributes a copy of the message to all subscribers that have registered an interest in that topic. Distribution of messages to subscribers may be either by point-to-point broadcast from the broker or by multi-casting. In the latter case, in order to reduce network traffic, messages on particular topics are distributed to intermediate shared addresses which are provided to all the subscribers that have registered an interest in the particular topic so that they can listen for newly published information.
A “topic” may be any character string that describes the nature of the data that is published in a publish/subscribe system. Topics are key to the successful delivery of messages. Instead of including a specific destination address in each message, a publisher assigns a topic to the message. The broker matches the topic with a list of clients (subscribers) who have subscribed to that topic and delivers the message to each of those clients. Topics can be defined by a system administrator in advance but can also be defined dynamically when specified in a publication for the first time.
Some message brokers include transformation engines at internal nodes that can transform a message into another form, for example, conversion of currencies for financial data. This relieves the end users from having to convert the message into a different format themselves. Additionally, customized transformations can be written by a user and applied externally of the broker. The topic message is transformed at the user application and republished back to the message broker, from where it can be sent on to subscribers to the transformed messages.
In the different field of television broadcasting and cinema film projection, a common ancillary feature is the provision of subtitles to accompany the main program or movie. A principal purpose is to provide a translation into a different language from the audio track or to provide same language subtitles for viewers with impaired hearing. Also known in current live television broadcasting is the use of captioning whereby further information relevant to the main program is either provided as a semi-static feature, for example giving a current game score, or is scrolled along the bottom of the screen to complement the main program content.
Subtitling and captioning are special effects provided directly by the broadcaster or movie maker. In the case of movie subtitling and so-called closed captioning for television, this may be outside the control of the viewer, who may not be able to select it or turn it off. Television subtitling, however, is normally provided by means of teletext and can be enabled by the viewer selecting the appropriate teletext channel.
US patent application publication 2005/0108026 A1 “Personalized Subtitle System” to Brierre et al. shows a user controllable subtitle facility for use in conjunction with a cinema film show, in which subtitles or captions are viewed through a heads-up display at the same time as the main film. Although primarily developed for a cinema audience, the possibility of using such a system for home DVD players or even live TV programs is mentioned. The subtitles are provided from a data base populated by publishers, aggregators or individuals and are provided by a central personal subtitle server to a controller for both the server and the heads-up display. The controller allows the user to switch the heads-up display on or off and to select different aspects of the subtitle, such as language, size, color, font and position. The possibility of personalized subtitle system controllers registering to receive only a group of subtitle packets at a particular group address is also mentioned without being explored further.